


let the devil in

by zora (nico_neo)



Category: Haikyuu!!
Genre: Alternate Universe - Canon Divergence, Angst, M/M, Mild Blood, Minor Violence, Past Relationship(s), Post-Break Up, spider-man sakusa, venom atsumu
Language: English
Status: Completed
Published: 2020-09-24
Updated: 2020-09-24
Packaged: 2021-03-07 18:21:04
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,186
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26632024
Author URL: https://archiveofourown.org/users/nico_neo/pseuds/zora
Summary: “Save him,” Osamu tells him. “No matter what it takes, save him.”“What if I can’t?” Kiyoomi asks him. “I’m the reason why he’s like this.”“You’re not,” Osamu shakes his head, blind eye seeing right through Kiyoomi’s core. “He willingly became evil. You’re just a number in one of the many equations that led to this.”Maybe it’s Kiyoomi who’s the villain, in the end.[Sakusa Week day 5: heroes/villains]
Relationships: Miya Atsumu/Sakusa Kiyoomi
Comments: 3
Kudos: 74





	let the devil in

**Author's Note:**

> this fic is solely inspired by that one scene in spider-man 3 (the spidey/venom fight)... i have no excuses it just FITS
> 
> i might write more spidey sakusa/venom atsumu... idk yet but this one was very cool to write!
> 
> Mention of blood and typical fight violence (well... with a pointy metal bar)!!
> 
> Enjoy!<3

Kiyoomi knows he has to make it stop. It can’t go on like this. He knows the damage this… suit, this evil entity can do to you. He was a first hand witness. It feeds on your despair. It sucks on your soul and negative feelings to become stronger, stronger and stronger. Until it eats you alive. Until you can’t let it go anymore. Until it becomes your second skin. No, until it becomes your skin. Until you become evil incarnate. A flying and walking carnage. Scattering disaster wherever you go. 

He knows. Kiyoomi knows it’s to get his attention. He knows it’s to provoke a fight. For Kiyoomi to come out of the shadows. He knows it’s for revenge. 

Kiyoomi knows Atsumu is just fulfilling his vengeance. Because of him.

Atsumu became _this_ because of him. 

Sweet, smiling, hard working Atsumu. Kiyoomi broke him. Kiyoomi made him end like this. Because of the same mistake. Because Kiyoomi wanted more. Because Kiyoomi acted selfish and was attracted to _power_. To success. He didn’t get rid of the symbiote like Wakatoshi told him to, and he paid the consequences. But, he didn’t realize that at first. He hadn’t realized it wasn’t power he had gained when the symbiote took over him and made his suit black instead of a vibrant purple over black. He hadn’t realized it was not power and strength he had gained when the symbiote took control of his personality. He hadn’t realized, back then, that the only thing that this suit brings with him is sorrow and madness. Kiyoomi had lost Atsumu that way. Atsumu had lost Kiyoomi over the suit. But Kiyoomi had also lost Atsumu over the suit. Nothing else mattered but the suit. Like an addict that didn’t get his dose.

When Kiyoomi got rid of the suit - of the symbiote - scratching his skin raw until it bleed for it to disappear, he didn’t think Atsumu would be the one to inherit it - the symbiote, the suit. He didn’t know Atsumu would be there, meters under him, crying his eyes out and praying for Kiyoomi to get back to him. 

Atsumu became a bloodthirsty monster because of him. The suit turned his weaknesses into forces and his despair into pure rage. Now, Kiyoomi is number one on Atsumu’s kill list, and the main goal of his revenge. Atsumu wants Kiyoomi _dead._ He is aware of that.

How do you save someone that completely lost himself? How do you save someone you have hurt to the core? How do you save someone that became like this because of you? How can you forgive yourself?

Kiyoomi doesn’t know. He doesn’t know if he will be able to save Atsumu. He might be able to… he is a hero after all. But what happens when you try to save someone that doesn’t want to be saved because they lost it all? What happens when you try to save someone that doesn’t want to be saved because they don’t have any hopes anymore?

How do you save the person you love but that you hurt so much that they want you dead?

Sometimes you can’t.

  
  


It’s everywhere on the news. The “monster black Spider-Man”. They don’t have a name. They don’t have a face. Simply a blurry picture of a black mass, swinging in the night, leaving blood behind him. It’s a message. It’s directed to Spider-Man. It’s directed to Kiyoomi.

 _Come out!_ was the first message. A young woman that was going home after work, at night. Wrong place, wrong time. She had black, viscous webs coming from her mouth. Don’t speak. 

_I know you’re here_ was the second message. This time, a student. He was probably going back from a party, tipsy or drunk. He also had black webs coming from his mouth. Don’t speak.

 _COME AND PLAY!_ It was the last message Atsumu had left behind. He left many more before this one, all resembling the previous ones. But this particular one was probably the more significant of them all. The victim was Kiyoomi’s boss. And Atsumu’s former one. Meian. From the local press department. Meian had fired Atsumu. Because of Kiyoomi. _I lost my job then you’re going to lose yours too._ Again, it was a reminder that all of this… It’s Kiyoomi’s fault. He did all of this. 

He’s the reason why Osamu was blind from his left eye, now. He’s the one who pushed Atsumu to hurt his own brother. He’s the reason why Osamu doesn’t have a brother anymore. His own weaknesses were the reason for this mess.

“Save him,” Osamu tells him. “No matter what it takes, save him.”

“What if I can’t?” Kiyoomi asks him. “I’m the reason why he’s like this.”

“You’re not,” Osamu shakes his head, blind eye seeing right through Kiyoomi’s core. “He willingly became evil. You’re just a number in one of the many equations that led to this.”

Maybe it’s Kiyoomi who’s the villain, in the end. 

“What are you going to do?” Miya asks him. Atsumu is shown on the screen of Osamu’s TV. Black suit covering his entire body. The only thing that distinguishes him from a simple black stain are the two greyish white eyes on his face. It looks like two flames. Evil. Pointy teeth replaced Atsumu’s bright ones. He’s doing carnage. Cutting police officers’ skin open with his claws. Buildings and cars are on fire around him. The crowd is screaming as the journalist is trying to recount what is actually going on.

“I don’t know,” Kiyoomi says, from next to Osamu. He’s already in his suit, only his head is free from his mask. Red and blue replacing plain, gloomy black. 

“Where is Spider-Man?!” he hears a man scream.

Kiyoomi puts the mask on and shoots a web, leaving Osamu standing in the living room of his apartment. His blind eye following Kiyoomi until he couldn’t see him swinging from building to building anymore.  
  


People notice him. They notice him coming. They all start clapping and cheering. And, obviously, Atsumu sees him too. Kiyoomi couldn’t see his face - replaced by an evil one, sharp teeth waiting to bite into his skin - but he could perfectly imagine the twisted grin that Atsumu must be bearing under his mask and set of canines. The way his pointy teeth lifted upwards already gives it away. Kiyoomi sees it before it happens. He knows what Atsumu is going to do. 

Atsumu places himself, ready to jump. Ready to attack the crowd. The moment he jumps with a devilish scream - the scream of evil incarnated - Kiyoomi swings further, faster. He places himself between Atsumu and the crowd. He pushes on Atsumu’s chest with his two feet thanks to the force of his swing. Atsumu goes flying away, towards the building under construction, and crashes somewhere in there. Kiyoomi doesn’t stop to salute and listen to the congratulations of the crowd and immediately shoots a web, swinging until he reaches the floor where he saw Atsumu crash in. 

Bricks and metal bars are scattered on the floor, but there is no Atsumu. It’s silent, too silent. Kiyoomi stays on his guards, ready to jump and defend himself. He hears roars. Atsumu. They’re spinning around him. He can’t tell where they’re coming from. From behind. From the sides. From the front. From under. From above. He doesn’t know. He hears another. And another. It’s getting close. But from where? 

Kiyoomi doesn’t have time to brace himself for the impact that Atsumu comes from higher up, grabs his neck with his claws and sends him smashing into the nearest girder, and then punches him during his fall, his back slamming against the brick pillar. Close to the edge. 

Atsumu watches him from above, crouched and roaring. Kiyoomi tries to stand up again, but Atsumu has already sent webs to his wrists, trapping him on his knees with his arms up. Atsumu punches him with a pointy metal bar, once. A demonic scream coming out of his throat. Twice, on the left side. And with another scream, on the right side once again. It sends his mask flying away and makes blood come out of his mouth. Kiyoomi spits the metallic taste out of his lips and teeth, and he lifts his eyes up to look at the man in front of him. Is he still a human… or did he already become a monster?

The black substance of the symbiote that was forming the mask slowly removes itself from his face. Strands of Atsumu’s golden hair come into view, even though most of it was hidden by the symbiote. Black lines still stick to his face, ready to form flaming eyes once again. Atsumu’s eyes are dark. Kiyoomi remembers them brown, with sparks of gold. They don’t shine anymore. Atsumu’s teeth aren’t perfectly straight and white anymore. Now, they are yellowish, his canines were way too long for a human being. Kiyoomi wants to call his name.

“You came, finally,” Atsumu hisses. His words only hold venom. Nothing like the warmth and the happiness they held whenever he was with Kiyoomi before. Now, it is only filled with anger, hatred. “Took you long enough.”

The pointy end of the metal bar hit his skin two more times. Kiyoomi feels blood running from his eyebrow. 

“Atsumu,” Kiyoomi breathes out. 

Atsumu only snickers, cackles like the disturbed being he became. “What is it, Omi?” he cackles again. “Didn’t ya understand by now to not wound what ya can’t kill?” he asks, and Kiyoomi feels the tip of the bar against his neck. Atsumu just has to push hard enough, and it’ll break his skin, right through his carotide. 

“You don’t have to do this,” Kiyoomi says, looking right at Atsumu. The other’s maniac smile never leaves his face. 

“Hm, yeah you’re right,” Atsumu pretends to think. “I’m thinkin’...” he pushes the bar deeper into Kiyoomi’s neck, but it’s still not enough to pierce the skin. “Nothin’ at all, the only way to pay you back for what ya did is to kill ya,” he growls. “Do ya even remember what ya did, Omi?”

“I hurt you, I know,” Kiyoomi exhales. “I was blind, and I hurt you, and I’m sorry.”

Atsumu laughs again. “Are ya really? Or are ya just scared to die?” He hits Kiyoomi again, in the chin. Kiyoomi coughs on the blood stuck in his throat. One of his hands has broken free under the assault, hanging loosely at his side. “Ya made me lose everything, Omi. I lost my life. Now I’m goin’ to make ya lose yer life too, how does that sound?”

“You’re not the only one who has lost something, Atsumu.”

“I’ve lost everything!” Atsumu screams. It’s filled with rage. Kiyoomi can understand. He was full of it too. Maybe he still is. But Atsumu is wrong. He hasn’t lost everything. He still has Osamu. He still has Kiyoomi. “What have ya lost, huh?”

“I’ve lost you.”

Atsumu only laughs. Not because it’s funny. Or maybe it is, to him. But his laugh is fake. Just like the Atsumu in front of Kiyoomi. It’s not the real Atsumu. It’s only a chimera. It’s only evil. Everything that Atsumu is not. Because that’s what that suit does to you. It brings out everything that is not who you really are and buries the good so deep it’s almost impossible to bring it back. 

He can’t reach him. There’s nothing human left in Atsumu. He is too late.

“The suit,” Kiyoomi croaks out, blood spitting from his mouth with every word he utters. “You need to take it off, Atsumu.”

“Oh, you’d love me to take it off,” he snickers, the pointy tip of the metal bar once again against Kiyoomi’s throat.

Kiyoomi swallows. He tastes blood. And that’s how this night is going to end. In blood.

“I know what it is,” he says. “I know what it feels like. You feel good. You feel powerful. You feel like nothing can stop you anymore,” he sees Atsumu’s brown eyes widen in agreement. “But it has a counterpart,” Kiyoomi continues. He doesn’t tear his gaze away from Atsumu's. Trying to reach into the deepest part of the dark orbs. “You lose yourself. You lose yourself until there’s no way back,” he gulps again. “Atsumu… Please, take it off.”

Atsumu shakes his head. The metal bar isn’t against Kiyoomi’s neck anymore. Atsumu raises it above him, over his head. The black fibers on his face start to snake close again as he takes several steps back. Like a predator ready to bounce on his prey. 

“I like being mad,” Atsumu offers him a last twisted smile before the filaments completely close. “It makes me happy.”

 _Happier than you made me_ is what Kiyoomi hears.

Mouth full of pointy teeth open in a furyish scream and eyes shaped like flames looking right at him, Atsumu jumps and sinks his handmade weapon down at the same time Kiyoomi shoots a web to the one lying abandoned behind Atsumu, hauling it towards them.

**Author's Note:**

> Thank you for reading ! \o/ 
> 
> Comments and kudos are my serotonin boost!
> 
> [Twitter](https://twitter.com/bokutowantsyou)  
> [curiouscat](https://curiouscat.qa/bokutowantsyou)  
> 


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